Conduit-slitting method

ABSTRACT

The invention contemplates a method and apparatus for longitudinally slicing tubular workpieces into separate parts which, for the case of cylindrical tubing, conveniently become semi-cylindrical halves. In specific application to flexibly sheathed, foamed-plastic tubing, the slicing action is complete at one local longitudinal alignment along the workpiece wall; but at the diametrically opposite local longitudinal alignment, the slicing action is radially outward to an extent short of severing the sheath, so that the sheath may hingedly connect the otherwise severed semi-cylindrical halves. As disclosed, the invention is applicable to continuous operation on successive lengths of tubing, in a conveyor-fed environment.

I States atem 1 1 1111 3,855,886

Andrews Dec. 24, 1974 CONDUlT-SLITTING METHOD 3,745,621 7/1973 Andrews83/9 x [75] Inventor: 326M101? E. Andrews, Kutztown, Primary ExaminerDonald R. Schran 7 Attorney, Agent, or Firm-Sandoe, Hopgood and [73]Assignee: Armstrong Cork Company, Calimafde Lancaster, Pa. 22 Filed:June 22,1973 [57] ABSTRACT The invention contemplates a method andapparatus [21-] App! N for longitudinally slicing tubular workpiecesinto sepa- Rela'ted US. Application Dat rate parts which, for the caseof cylindrical tubing, 62 7 f5 N '282,653,, 12 1972 P L N convenientlybecome semi-cylindrical halves. In spe- 2 7; 1; er 0 Hg 3 O cificapplication to flexibly sheathed, foamed-plastic tubing, the slicingaction is complete at one local lon- 52 us. c1 83/7, 83/9, 83/54giwdinel alignment along the workpiece well; but at 51 Int. Cl. B26d1/02 the diametrically pp leeel longitudinal align- [58] Field of Search83/1, 54, 7, 8, 9, 10, meet, the Slicing eerie is radially Outward to an83/180, 29/235 tent short of severing the sheath, so that the sheath Imay hingedly connect the otherwise severed semi- 5 R f n Citedcylindrical halves. As disclosed, the invention is appli- UNITED STATESPATENTS cable to continuous operation on successive lengths of tubing,in a conveyor-fed environment. 3,577,889 5/1971v Er1ksen.....,.. 1 83/54X 3,715,941 6 Claims, 8 Drawing Figures 2/1973 Andrews 83/7CONDUIT-SLITTING METHOD This application is a division of my copendingapplication Ser. No. 282,653, filed August 22, I972 now U.S. Pat. No.3,799,012.

The invention relates to a method and apparatus for the mass-productionlongitudinal slicing of a succession of tubular. workpieces, such asflexibly sheathed foamed-plastic tubing produced by techniques describedin Snelling U.S. Pat. No. 3,1 18,800, issued Jan. 21, 1964. v

In the slicing of tubing of the character indicated, it has been thepractice to individually chuck each workpiece for exposure to slicingtools which are reciprocated in both advance and return strokes over thefull length of the workpiece, before the workpiece can be removed toenable a recycling. While the resulting product is of acceptablequality, the costs of individual workpiece handling and of multiplestrokes become significant economic factors.

It is, accordingly, an object of the invention to provide an improvedmethod and apparatus of the character indicated, wherein the indicatedfactors are eliminated or substantially reduced.

Another object is to meet the above object with continuousunidirectionally operative process.

A further object is to provide such a machine wherein a continuoussuccession of workpieces may be automatically sliced.

Still another object is to provide such a machine which is selectivelyadaptable to performing functionally similar slicing operations on avariety of workpiece sizes.

A still further object is to provide such a machine wherein workpiecelength is not a limiting factor.

' A general object is to achieve the above objects with basically simplestructure which will produce at large volume and with sustainedaccuracy.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification in conjunction with the accompanyingdrawings.-

In said drawings, which show, for illustrative purposes only, apreferred form of the invention:

FIGS. 1, 2 and 3 are simplified end views of a workpiece, to illustratea succession of steps performed by the invention;

FIG. 4 is a front perspective view of the working part of a machine ofthe invention, set for operation on a workpiece of relativelylarge-diameter;

FIG. 5 is a rear perspective view of the machine shown operating on asmaller-diameter tubular workpiece W;

FIG. 6 is a simplified view in elevation of the entire machine;

FIG. 7 is an enlarged fragmentary view in elevation of tool-supportingstructure of the machine; and

FIG. 8 is an enlarged fragmentary view, taken at the section line 8-8 ofFIG. 6.

FIGS. 1, 2 and 3 serve to identify the structure of an illustrativetubular workpiece and the successive operations performed thereon, inaccordance with the invention. The workpiece, as formed by techniques ofsaid Snelling patent, is a given cut-off length, for example, afour-foot length, of cured foamed urethane or the like plastic 10,constituting the primary insulating body or bulk, between an inner papersheath 11 and an outer sheath 12, preferably cloth-reinforced, forflexibility and durability. The outer sheath 12 may be a laminatedcomposite of metal foil, paper, and the reinforcement cloth. Bothsheaths 11-12 are bonded to the foamedplastic body 10, the outer sheath12 continuously enveloping the same from an inner starting point 13 toan outer limit 14 of bonded overlap; beyond location 14 the outer sheath12 comprises an unbonded flap 15 extending at least the circumferentialdistance Sbeyond an unbonded location 16 at which a slicing operation isto be performed. I

FIG. 2 illustrates that initially the flap 15 is folded back on theadjacent bonded region of sheath 12 so as to expose the radial alignment16 for slicing, without harm to the flap 15. FIG. 2 also serves toillustrate that a first slicing step in the inventive method involves aradial cut 17, from the inside and radially outward, to a location whichis just short of the outer sheath 12. As will later be more'clear, thiscut is performed by a radially oriented knife blade, held by an elongatestem and tool holder, extending longitudinally in the bore of theworkpiece. The cut' 17 is thus through the inner sheath and throughvirtually the entire body-wall thickness of the foamed material 12, itbeing noted that .at the longitudinal location atwhich cut 17 is made,the remaining circumferential extent of the body 10 and both sheaths1l12 remains intact, thus retaining body-shape and position controlwhile the slice, 17 is being made.

FIG. 3 illustrates the subsequent step of performing a second radialslice, at a location longitudinally removed from'that at which slice 17is made, and, therefore, at a time subsequent to that of forming slice17.

Slice 18 is preferably in the same axial plane as slice 17, I

being at location 16 and; therefore, slightly offset from the bent-backflap 15. The resulting product comprises like semicylindrical halvesA-B, hingedly connected by flexible sheath material at C, and equippedwith a free flap 15 by which the alignment 16 of adjacent body faces (atslice 18) may be overlapped after the product has been applied to a pipeof outside diameter to fit the bore of the product. j

'In FIGS. 4, 5 and 6, the machine of=the invention is seen to comprisean elongate generally horizontal guide frame 20 extending between spacedfloor-mounted pedestals 21-22 each of which carries pulley means 23-24for the guidance and support of the upper stretch 5? an endless conveyorloop 25. Theloop 25 may be a sprocket chain, belt-driven from a motor Mto the shaft of pulley means 24. The direction of drive is such as tounidirectionally progress the upper stretch of the conveyor loop 25 inthe left-to right direction, in the sense of FIG.- 6, as shown byarrows. In FIGS. 4 and 5, each link of the conveyor loop is seen toinclude a flat laterally extending plate 26, having laterally outwardprojecting ends which derive .support from opposed flanges 27 of theguide means 20- which forms part of the machine frame. The connectedadjacent link elements of the conveyor are of lesser lateral extent andare guided by and between the spaced adjacent edges of flanges 27. Theconveyor 25 is completed by provision of work-engaging lug members 28'atspacings exceeding the anticipated unit-length of the workpieces; asshown in FIG. 4, a lug member 28 may be the formed-up edge of one of theplates 26, with a'wideslotted central region, to avoid interference witha slicing tool.

Aside from the upper longitudinal stretch of the conveyor 25, thework-positioning means of the machine comprises stabilizing elements orrails 30-31 which extend parallel to each other and to the guide'means'20 throughout a work-stabilizing region, between upright girder frames32-33 at spaced central locations along means 20. Each girder framecomprises two upright channels 34-35, secured by spacers 36 to frame 20,at equal wide lateral offsets on opposite sides of the central verticalplane of symmetry of the guide means 20. A flanged girder 37 unites theupper ends of the channels 34-35, and the open dimensions within thegirderframe enclosures 32-33 are selected to'amply accommodate thelargest-diameter workpiece anticipated for the machine. Threaded rods39, brazed to rails 30-31 at appropriate spacing, are lock-nutted toselected apertures in channels 34-35, each channel bottom being. drilledwith a series of vertically spaced apertures, whereby the elevation ofrails 30-31 may be adjustably selected, as appropriate for the diameterof workpieces to be sliced. Further rail-positioning adjustment isafforded by the lock-nutted clamping of rods 39 to channels 34-35, tothe end that rails 30-31 in the region 32-33 shall be spacedsubstantially by the diametral extent of the workpiece; preferably, thisregion 32-33 extends longitudinally to an extent substantially exceedingthe largest diameter of workpiece handled by the machine. As shown'inthe foreground of FIG. 4, the rails 30-31 diverge at the mouth or workentrance, being positioned by adjustable jack means 40 atan appropriateaperture elevation on spaced further uprights 41.

For larger-diameter workpieces, i.e., the situation depicted in FIG. 4,a central longitudinally extending flange girder 42 is bolted to thecenters of the upper girders of both frames 32-33, thus rigidly unitingthese frames and providing greatest work clearance within the frames.For smaller-diameter workpieces, an intermediate bar or girder member-43is secured to both channels 34-35 of each frame 33-33, at an intermediorrails 30-31,the frames 32-33 serve the additional function of supportingthe tool-positioning means, the

- tools being shown as first and second knife-blade eleble of slicingbodyand both sheaths 11-12 at location 16, to define the upper slice 18.

The other tool holder means, i.e., for tool 45,.comprises a radial strutportion 48, adjustably secured to support member 42, and alongitudinally extending stem portion 49 whereby a holder 50 for tool 45may be positioned in longitudinally forwardly offset relation, i.e.,forwardly of the mounted longitudinal location of tool 44. Preferably,the extent of such longitudinally forward offset, of the lower tool 45with respect to the upper tool 44, is at least in the order of theworkpiece bore diameter. As shown, the stem portion 49 comprises twosteel straps, with width dimensions vertical, and oriented face to face,so as to clamp the toolholder plate 50at the forward end and to clampthe strut 48 at the rear location. Generally, the set-up of thetool-positioning elements places the stem portion 49 at the center ofthe workpiece, with ample clearance to the workpiece bore,-and so as toenable blade 45 to make the restricted work entry described at 17 inconnection with FIG. 2.

FIG.- '7 provides further detail of construction for strut 48, which isseen to comprise a flat plate, having raked leading and trailing edges52-53 which are tapered for non-fouling passage through the slit (18)path 1 developed by the upper tool 44. Preferably, theforments 44-45,both of which have sharp cutting edges support element of thetool-positioning means. To this end, first tool-holder means 46serves-the upper blade 44, said means 46 being formed-in or secured tothe forward end of member 42. The set-up elevation of support member 42should be such that the tool 44 which is thereby positioned will definea slicing plane at location 16 (see FIG. 1), i.e., such that the cuttingedge of blade 44 is in the central vertical plane of symmetry'of theguide means 20; at the same time, the elevation is so selected thatblade 44 will intercept only the adjacent upper wall thickness of theworkpiece, spanning the inner and outer radii and, therefore, capawardlongitudinal offset of tool 44 ahead of strut 48 is at least in theorder of the diameter of the workpiece, as appears from the proportionsin FIG. 6. Radial adjustment of strut 48 is afforded by two sets ofdrilled mounting apertures 54-55, both passing through the maximumstrut-body thickness. The rear apertures 55 serve a pivot function, forconnection the the support member 42 so that a vertical jack-screw 56 ina bracket 57 carried at an upper forward part of the strut body' I willfully secure the adjusted tool 45) elevation set-- ting- In use, andassuming correct stabilizer adjustment and tool-holder positioning forthe intended workpiece size, successive workpieces W are applied toconveyor 25 at the load region L (FIG. 6), forward of each succeedingfeed lug 28, and angularlyoriented to place the alignment 16 in slightlyoffset relation to the adjacent fold of flap 1-5. The flared mouth ofrails 30-31 quickly establishes a stabilized central orientation of theworkpiece and retains the same for its full passage through the slicingregion, and if desired, one or more longitudinally spaced spring fingerelements, as at 58, may vbe secured to member 42 to assure lightresidual downward loading pressure on the workpiece throughout theslicing operation.

The lower tool 45, being forward of the upper tool, first establishesthe precision limited-entry cut, '17, while circumferential integrity isretained at the longitudinal location of this first tool cut.Thereafter, the upper tool 44 fully slices the upper and diametricallyopposite tubewall, at 18, as already described. Finally, the finishedproduct is retrievable at a downstream location R, or it may simply beprojected off the end of the conveyor loop 25, as it rounds the drivepulley means 24.

' It will be seen that the described machine and method meet all statedobjects. In practice, the product adheres to close tolerancerequirements, as to depth of the cut 17 and as to alignment of the upperslice 18. Adjustment for a changeover of workpiece size is readilyaccomplished with simple mechanics tools.

While the invention has been described in detail for the preferred formshown, it will be understood that modifications can be made withoutdeparture from the scope of the invention.

What is claimed is:

l. The method of longitudinally dividing a flexibly sheathed tubularworkpiece into hinged semicylindrical halves, which comprises firstradially outwardly slicing the workpiece wall on a longitudinalalignment locally proximate to the desired hinge axis and to a radialextent short of severing the sheath, and thereafter radially slicing adiametrically opposite locale of the entire workpiece wall on alongitudinal alignment parallel to said first alignment, whereby at thelocal region of first slicing action the local integrity of theremaining circumferential extent of the workpiece body provides astabilizing action to assist in accurate control of said radial extent,so that hinge action cannot be available until a point in time aftercompletion of the entire firstand second-slicing action is at least inthe order of the bore size of the workpiece.

3. The method of claim 1, in which the steps of firstslicing action andsecond-slicing action are performed simultaneously on the workpiece andin longitudinally offset relation along the workpiece.

4. The method of longitudinally dividing a flexibly sheathed tubularworkpiece to form hinged arcuate cylindrical segments, whichcomprises'first radially outwardly slicing the workpiece wall on alongitudinal alignment locally proximate to the desired hinge axis andto a radial extent short of severing the sheath, and thereafter radiallyslicing an angularly offset locale of the entire workpiece wall on alongitudinal alignment parallel to said first alignment, whereby at thelocal region of first slicing action the local integrity of theremaining circumferential extent of the workpiece body provides astabilizing action to assist in accurate control of said radial extent,so that hinge action cannot be available until a point in time aftercompletion of the entire first-slicing action. I

5. The method of claim 4, in which each of said slicing steps isperformed in a longitudinal traverse of the workpiece.

6. The method of claim 4, in which both said slicing steps are performedin the same longitudinal traverse of the workpiece, the first-slicingaction being longitudinally forward of said second-slicing action insaid traverse.

1. The method of longitudinally dividing a flexibly sheathed tubularworkpiece into hinged semicylindrical halves, which comprises firstradially outwardly slicing the workpiece wall on a longitudinalalignment locally proximate to the desired hinge axis and to a radialextent short of severing the sheath, and thereafter radially slicing adiametrically opposite locale of the entire workpiece wall on alongitudinal alignment parallel to said first alignment, whereby at thelocal region of first slicing aCtion the local integrity of theremaining circumferential extent of the workpiece body provides astabilizing action to assist in accurate control of said radial extent,so that hinge action cannot be available until a point in time aftercompletion of the entire first-slicing action.
 2. The method of claim 1,in which the longitudinal offset between the performance offirst-slicing action and second-slicing action is at least in the orderof the bore size of the workpiece.
 3. The method of claim 1, in whichthe steps of first-slicing action and second-slicing action areperformed simultaneously on the workpiece and in longitudinally offsetrelation along the workpiece.
 4. The method of longitudinally dividing aflexibly sheathed tubular workpiece to form hinged arcuate cylindricalsegments, which comprises first radially outwardly slicing the workpiecewall on a longitudinal alignment locally proximate to the desired hingeaxis and to a radial extent short of severing the sheath, and thereafterradially slicing an angularly offset locale of the entire workpiece wallon a longitudinal alignment parallel to said first alignment, whereby atthe local region of first slicing action the local integrity of theremaining circumferential extent of the workpiece body provides astabilizing action to assist in accurate control of said radial extent,so that hinge action cannot be available until a point in time aftercompletion of the entire first-slicing action.
 5. The method of claim 4,in which each of said slicing steps is performed in a longitudinaltraverse of the workpiece.
 6. The method of claim 4, in which both saidslicing steps are performed in the same longitudinal traverse of theworkpiece, the first-slicing action being longitudinally forward of saidsecond-slicing action in said traverse.